Good books on poetry

Looking at my bookshelf, I have a number of books I'd highly recommend to anyone on writing or reading poetry, as well as a few books I don't own but can also recommend.

So here is the beginnings of a list of good books on poetry. These are listed in order of preference and will be expanded over time:

Shaw, Robert. (2007). Blank Verse : a guide to its history and use. Athens, Ohio: Ohio University Press
A detailed, ambitious focus solely on iambic pentameter since its origins in the sixteenth century, and particularly valuable for covering 20th and 21st century poets that have written in blank verse, such as Howard Nemerov and Rachel Hadas. Essential if you want to understand the form.

Fussell, Paul. (1979). Poetic Meter & Poetic Form. Revised Ed. McGraw-Hill.
Informative book on meter, and yes, form, that's well-written and actually shows how meter and form create meaning as well as the rest of the poem. A useful reference book for readers and every poet or would-be poet should have read this or a similar book.

Keats, John. (2001). Selected Letters 1817-1820. In Complete Poems and Selected letters of John Keats. New York: The Modern Library.
This edition is only one of many published. These letters show the development of Keats' poetic career, knowledge, maturity, and understanding of poetry itself. It's in these letters he discusses the famous concept of "Negative Capability".

Rilke, Rainer Maria. (2004). Letters to a Young Poet. Translation by Herter Norton, M.D. Revised Ed. New York / London: W.W. Norton & Company.
Again one of many publications. Letters written by Rilke to a would-be poet from 1903-1908. Rilke has a sensitive way of describing sensibility, and poetic and life choices, and is unabashedly emotional about it. If you feel jaded and too intellectual about your poetry, this could be an inspiring read.

Hirsch, Edward. (1999). How to Read a Poem : and Fall in Love with Poetry. Houghton Miffler Harcourt.
In my mind I always add "..all over again." to the end of the title. Another wonderful book for fresh enthusiasm and reading poetry you might not otherwise read. Also informative. The first chapter can be read on the Poetry Foundation website.

Kowit, Steve. (2003). In the Palm of Your Hand : the Poet's Portable Workshop. Atlantic Books.
The cover calls this "lively", and it is. Kowit aims to reach both new and experienced poets, covering just about everything you could imagine in a small volume. Because it's a general guide I would suggest it to inexperienced poets first, readers second, and everyone else when they feel the need to do some general reading again.